Liquid level sensor

• US 6,408,692 B1
• Filed: 11/20/1997
• Issued: 06/25/2002
• Est. Priority Date: 11/20/1997
• Status: Expired due to Fees

• Current Assignee: Isspro, Inc.
• Original Assignee: Isspro, Inc.
• Inventors: Glahn, Gary W.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): CYGAN, MICHAEL T
• Application Number:
  US08/975,180
• Time in Patent Office: 1,678 Days
• Field of Search: 738/641.3, 733/14, 733/13, 731/13, 733/05, 732/90.R, 340/450.2
• US Class Current: 73/313
• CPC Class Codes: G01F 23/303 characterised by means to prevent fault-level readings due to turbulence of the fluid, e.g. special float housings
• CPC Class Codes: G01F 23/74 for sensing changes in level only at discrete points

Abstract

A liquid level sensor is provided that comprises an integral housing including therein a pickup tube, a return tube and a float cavity with a float positioned therein. Sensors are positioned within the float cavity for sensing the position of the float so as to determine the level of liquid within a tank or the like.

Claims

1. A combined liquid level sensor and liquid pickup and return, comprising:

an elongate housing that defines therein a pickup cavity, a return cavity and a substantially enclosed float cavity, said housing having a longitudinal axis, wherein said pickup cavity, said return cavity and said float cavity are sealed with respect to one another along said longitudinal axis; and

a float positioned within said substantially enclosed float cavity and adapted for movement therealong,

wherein said pickup cavity and said return cavity are substantially parallel to one another and substantially coextensive with one another,

wherein said float cavity is defined between said pickup cavity and said return cavity,

wherein said float cavity is substantially parallel to said pickup cavity and said return cavity, and

wherein said float cavity is substantially coextensive with said pickup cavity and said return cavity.

2. A combined liquid level sensor and liquid pickup and return according to claim 1 further comprising a sensor positioned within said float cavity for sensing the position of said float within said float cavity.

3. A combined liquid level sensor and liquid pickup and return according to claim 2 wherein said sensor comprises a plurality of switches.

4. A combined liquid level sensor and liquid pickup and return according to claim 3 wherein said float includes a ferromagnetic material and ones of said plurality of switches comprise magnetically actuated switches.

5. The combined liquid level sensor and liquid pickup and return according to claim 1 further comprising damping means for damping fluctuations of a liquid level within said float cavity.

6. A combined liquid level sensor and liquid pickup and return according to claim 5 wherein said damping means comprises an end of said housing having an aperture therein, said aperture providing for communication between said float cavity and an exterior of the housing and being of a size so as to dampen the effect on a liquid level within the float cavity of sudden fluctuations in a liquid level exterior of the housing.

7. A combined liquid level sensor and liquid pickup and return according to claim 1 wherein said float cavity includes ribs positioned therealong for facilitating movement of said float along said float cavity.

8. A combined liquid level sensor and liquid pickup and return comprising:

a housing that defines therein a pickup tube, a return tube and a substantially enclosed central cavity as an integral unit, there being substantially no fluid communication between either said pickup tube or said return tube with respect to the central cavity, said pickup tube, said return tube and said central cavity being substantially coextensive with one another; and

a circuit board positioned within said central cavity and including thereon a plurality of position sensors.

9. A combined liquid level sensor and liquid pickup and return according to claim 8 further comprising a float positioned within said central cavity and adapted for movement therealong.

10. A combined liquid level sensor and liquid pickup and return according to claim 9 wherein said float is a closed cell foam float including a ferromagnetic material enclosed substantially entirely within the closed cell foam.

11. A combined liquid level sensor and liquid pickup and return according to claim 8 further comprising an endcap having an aperture therein, said aperture providing for communication between said central cavity and an exterior of the housing and being of a size so as to damp the effect on a liquid level within the central cavity of sudden fluctuations in a liquid level exterior of the housing.

12. A combined liquid level sensor and liquid pickup and return according to claim 9 wherein said central cavity includes ribs positioned therealong for facilitating movement of said float along said central cavity.

13. A combined liquid level sensor and liquid pickup and return comprising:

an elongate integral housing that defines therein a pickup cavity, a return cavity and a substantially enclosed liquid level cavity, said pickup cavity, said return cavity and said liquid level cavity being substantially coextensive with one another, fluid communication being substantially absent between said pickup cavity or said return cavity and said liquid level cavity along the extent thereof;

a sensor positioned within said liquid level cavity; and

a liquid level sender positioned within said liquid level cavity and adapted for movement within the liquid level cavity for indicating the liquid level to the sensor.

14. A combined liquid level sensor and liquid pickup and return according to claim 13 wherein said sensor comprises a plurality of proximity switches actuated by said liquid level sender.

15. A combined liquid level sensor and liquid pickup and return according to claim 13 wherein said liquid level sender is a closed cell foam float.

16. A combined liquid level sensor and liquid pickup and return according to claim 14 wherein said liquid level sender is a closed cell foam float including a ferromagnetic material enclosed therein for actuating ones of said proximity switches.

17. A combined liquid level sensor and liquid pickup and return according to claim 13 further comprising an endcap having an aperture therein, said aperture providing for communication between said liquid level cavity and an exterior of the housing and being of a size so as to damp the effect on a liquid level within the liquid level cavity of sudden fluctuations in a liquid level exterior of the housing.

18. A combined liquid level sensor and liquid pickup and return according to claim 13 further comprising a dampener for damping the rate of liquid level changes within said liquid level cavity.

19. A combined liquid level sensor and liquid pickup and return according to claim 13 wherein said liquid level cavity includes at least one rib extending along at least a portion of said liquid level cavity.